Conventional underwater thermometers are based on a bimetallic coil which causes an indicator to move around a circular path, with the degrees of temperature indicated on a circular dial. Such thermometers are often made to be worn on a wrist band, in a manner similar to a wrist watch. While fluid and tube type thermometers are well known for other uses, as far as known, there is no underwater thermometer available on the market of this type.
Applicants have produced a thermometer for hikers, campers, and the like, utilizing the body of FIGS. 7-12 of U.S. Pat. No. Des. 241,727 by attaching a fluid and tube type thermometer to an opaque plastic layer and placing the layer in the generally rectangular recess of FIG. 12 of such design patent. This layer had .degree.F. and .degree.C. scales printed on the surface adjacent the thermometer which extended into the central slot of FIG. 12 of the aforesaid design patent, with the bulb in the enlargement shown. The rim around the recess was then heated to fuse with the layer and to seal all edges of the layer. This thermometer would withstand rain showers when attached to a jacket or other clothing of a user, but when immersed in water, would permit water to leak into the thermometer cavity, with the possibility of the thermometer becoming dislodged and inaccurate readings result.
Among the objects of this invention are to provide an underwater thermometer which will not only withstand prolonged immersion in water but also in water at pressures at depths to which divers with normal air tank equipment will go; to provide such an underwater thermometer which utilizes a fluid and tube type of indicator; to provide such an underwater thermometer which is light in weight and relatively inexpensive in cost; to provide such an underwater thermometer which is readily observed and the indication of the temperature readily seen against various backgrounds; to provide such an underwater thermometer which is light in weight and readily constructed; to provide such an underwater thermometer which may be formed from a readily moldable material, such as plastic, which is not only light in weight but transparent; and to provide such an underwater thermometer which is only relatively easy to produce but also effective and long lasting in use.